Uso de Mapas Conceituais: percepções sobre a construção de conhecimentos de estudantes do ensino médio a respeito do tema radioatividade / Using Concept Maps: perceptions about building knowledge of highschool students on the radioactivity subject

Este trabalho destina-se a investigar as contribuições dos mapas conceituais na análise da construção do conhecimento relacionado ao tema Radioatividade no ensino de Química com estudantes do terceiro ano do ensino médio, tendo como paradigma teórico a Aprendizagem Significativa de David Ausubel. Tal teoria compreende que o aprendiz se apropria do conhecimento, por elaboração pessoal, a partir de conceitos pré-existentes em sua estrutura cognitiva, que vão se modelando e se aprimorando por diferenciação progressiva e/ou reconciliação integrativa no decorrer do processo de ensino e aprendizagem. Partindo dessa teoria, Joseph Novak desenvolveu a metodologia de mapas conceituais, no sentido de representar como o conhecimento é armazenado na estrutura cognitiva de um estudante. Utilizando como categorias de análise a diferenciação progressiva e a reconciliação integrativa,mapas conceituais de dois estudantes, antes e depois da referida unidade temática, são estudados para a compreensão da organização conceitual que os estudantes atribuíram ao tema. As análises mostram que os mapas conceituais constituem-se em recurso privilegiado de acompanhamento do processo ensino e aprendizagem dos estudantes por seus educadores.

This study aims to investigate the contributions ofconceptual maps in the analysis of the construction of knowledge related to the topic Radioactivity in chemistry teaching. Theoretical paradigm of Meaningful Learning from David Ausubel study wasutilized with students of high school (third year). This theory includes the learner appropriates the knowledge, personal development, from pre-existing concepts in their cognitive [structure,which will be shaping and tweaking by progressive differentiation and/or integrative reconciliation in the process of teaching and learning. Based on this theory, Joseph Novak developed the methodology of conceptual maps, to represent how the knowledge is stored in the cognitive structure of a student. Conceptual maps of two students before and after thisthematic unit were studied using as categories of analysis the progressive differentiation and the integrative reconciliation. These aspects were used for understanding the conceptual organization that students assigned to the radioactivity theme. The analysisshows that concept maps are a privileged resource monitoring the teaching and learning processes of students by their teachers

Effect of mobile phone microwaves on fetal period of BALB/ c mice in histological characteristics of hippocampus and learning behaviors

The possible risks of radio-frequency electromagnetic fields [EMF] for the living organisms and human body are a growing concern for our society. In this study, we examined the possibility of changes in working memory and hippocampal histological characteristics effects in mice brain following whole body exposure to microwave radiation. During gestation period, we exposed mice for 4 hr to Global system for mobile communications [GSM], Specific Absorption Rate [SAR] of 200 mW/kg. Pregnant control mice were sham-exposed or free in a cage without further restraining. Three month after exposure, animals were prepared for behavioral [Radial Arm Maze [RAM] and Morris Water Maze [MWM]] and histological studies. The showed that microwave exposed mice were slower than sham, and control in finding the platform. Analyses of error rates in RAM and MWM performance revealed significant differences which emphasize the effect of acute exposure to pulsed microwaves in deficit of spatial reference memory in the mice. However in this study exposed group didn't show any statistically significant loss of hippocampal CA1, CA3 neurons versus controls or sham. We conclude that there is evidence from the current study that exposure to MW radiation under parameters examined caused decrements in the ability of mice to learn the spatial memory task

[Effect of cell phone radiation [940 MHz] on the learning and memory of Balb/c mice]

The possible risks of radio-frequency electromagnetic fields for human body are a growing concern for our society. In the modern world, the increase of using cell phones is remarkable in all generations especially young people. In addition many users hold phone close to their head. Therefore, we have studied the effect of cell phone radiation [940 MHz] on memory and learning of Balb/C mice which were exposed after delivery. A purpose-designed exposure at a specific absorption for 3h/day from day 1 to 20 after delivery was used. Any stress response in the brain was detected in hippocampus. Behavioral performance began 2.5 month after delivery and testing was conducted in the water maze and the radial maze distinguished working and reference memory performance. After behavioral studies, fetal heads were collected, fixed in 10% paraformaldehyde and paraffine embedded. Microwave-exposed mice were slower than sham-exposed, and cage control in swim speed [WM]. Error Analyses rates reveal significant exposure effect in RAM and MWM. However, in this study the exposed group had not significantly lost their hippocampal CA3 neurons comparing to controls or sham exposed group. Increased time to locate a submerged in water maze, reference memory [entries into unbaited arms], working memory [repeated entries into baited arms], show that acute exposure to pulsed microwaves caused a deficit in spatial reference memory in the mouse

Long-term effect of prenatal exposure to low level of gamma radiation on neurophysiology of mouse.

Abdominal region of pregnant Swiss mice were exposed to 0.25, 0.35 or 0.50 Gy of gamma radiation on days 11.5, 12.5, 14.5 or 17.5 post coitus (pc). Changes in locomotory activity and learning performance, and hippocampal biogenic amines (noradrenaline, NA; dopamine, DA; 5-hydroxytryptomine, 5-HT; and 5-HTs metabolite 5-hydroxyindolacetic acid, 5-HIAA) were studied at 12 (adult) and 18 months (old) of age. Significant change in locomotory activity and learning performance was observed after exposure to 0.50 Gy at late organogenesis day (11.5 pc), when tested at 12 months of age, but not observed much change at 18 months. Biogenic amines did not show any significant change after any exposure dose at any of the gestation days. It was inferred from the results that gamma irradiation (0.50 Gy) at the late organogenesis (day 11.5 pc) can impair the brain functions in adults when normal faculties are functional.